


Oh Cum On

by wearyeyebrow



Category: Undertail - Fandom, Undertale (Video Game)
Genre: Coitus Interruptus, Ecto-Penis (Undertale), Ecto-Vagina (Undertale), Established Relationship, F/M, Gentle femdom, Hand Job, Implied Dom Reader, Oral Sex, Reader's POV, Slice of Life, Squirting, Sub Sans, Vaginal Fingering
Language: English
Status: Completed
Published: 2017-01-19
Updated: 2017-01-19
Packaged: 2018-09-18 12:37:11
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,951
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/9385502
Author URL: https://archiveofourown.org/users/wearyeyebrow/pseuds/wearyeyebrow
Summary: Life is a strange and wonderful thing. You live, you die, you make jokes about cacti, and sometimes you just can't catch a break. Will you ever orgasm? Who knows? I certainly don't.This involves sub Sans, my favorite subject, going through just another day in the life. Written in 2nd person from the reader's perspective. The sex is peppered throughout. Hope you enjoy!





	

It’s been one of those days.

You’re tired, you're damp, and you feel like a moldy piece of bread. The kind that goes off just before its expiration date.

The rain drizzles on as you walk to your car.

No one was happy with your performance at work, so you were stuck doing damage control, consoling clients, and fixing projects.

You feel lacking.

You sit in traffic for an hour because there’s been an accident. Hey, there’s something to be happy about - at least you’re alive.

And home isn’t too far away.

Home is where you have cold leftovers, and national geographic reruns. Home is where your boyfriend should be right about now – you always get together on Friday nights. It’s just tradition. 

Your brakes squeal in the driveway – you make a mental note to get that checked out, just like any other night.

You close the front door behind you and toe off your shoes.

The first thing you see is Sans.

And he’s squinting at your cactus.

‘…what are you doing?’

‘cact-eyeing.’

‘What the hell is cact-eyeing?’

‘interrogation; this one’s pretty sharp. i’ve got nothing so far.’

You laugh and lean against the door, the stress of the day settling on the floorboards. 

‘How long were you standing there waiting to make that joke?’

‘not long. i heard your footsteps in the driveway.’

‘And how long have you been planning it?’

He shrugs, ‘i was inspired in the heat of the moment. you gonna come in, or…?’

You look around you, ‘Nah, think I’ll stay here. It's got a great view - did my property taxes go up?’ You wiggle your eyebrows. You’ve got just as many horrid pickup lines.

‘welp,’ he turns on his heel, ‘more fried rice for me.’

‘Now let’s not get hasty-’

He chuckles, already in the kitchen.

-

The two of you sprawl on the couch, takeout boxes in hand. You ask him about his day, and you’re glad that he’s had a good one. Papyrus has Alphys and Undyne over for the night. They’re trying to get ‘convention ready.’ You wonder what they’ll go as this year.  

But the sting of the day still leaves a bad taste in your mouth as you pick at your food.

‘hey.’

You feel his foot nudge your thigh, ‘Hm? Oh, sorry.’

He shakes his head, ‘what’s up?’

‘I’ve just got some stuff on my mind.’

‘yeah?’

‘It’s not a huge deal or anything, just frustrating.’ You get up and put your box back in the fridge, plop down next to him, and sink deep into the couch cushions.

‘wanna talk about it?’

You tilt your head against the backrest. ‘It’s more like a feeling than anything specific. A feeling I can’t put into words yet – I mean… I know I’ll only be at this job for a couple more months. So, it’s inconsequential in the whole scheme of things. But I just… Maybe I just feel overwhelmed. Or maybe I just feel like I’m not doing enough. Who knows. I don’t want to think about it tonight.’

‘okay, that’s fine.’ You rest an arm over the back of the couch. ‘but you, uh… if that’s the case, then maybe i can redirect your attention?’

You raise an eyebrow. ‘Yeah? On what?’

‘uh...’ he looks to the side. ‘…i’m not very good at this part, am i?’

You brush your knuckles against his skull. ‘Nah, you’re perfect to me.’

‘now see, that was smooth.’ He clears his throat.

Ah, he’s easy to sink into. You want him to be happy, to be the one that makes him happy. It means you’re doing something right. That you’re needed somewhere.

‘again, it’s cool if-’

‘I want you.’

He looks at you quizzically. ‘i mean… you have me already.’

‘In what way?’

‘in any way you want.’

Heat spreads between your legs. He knows just what to say, doesn’t he?

He lets you push him back into the couch and crawl over him, no resistance, welcoming you. What do you want? What would make him feel the best? What does he like? You want whatever will continue to make him look at you like he is right now.

You deliberate. ‘I wanna take my time… Wanna see how many times I can get you to come for me.’

‘yeah?’

‘Yeah, so why don’t I give your cunt some attention?’

He lets out a shaky breath, ‘that’s uh, more than okay with me.’

-

You lose track of time as you work your way around his body. Every part of him gets some attention. You focus on all of the spots you know he likes, the ones that make him lean into you, the ones that make him shudder. You aren’t going slow tonight, but you are taking your time.

He’s dripping by the time you get between his legs and press your face into his cunt. After a bit of coaxing, some soft words, and a little attention from your tongue, he gives in, and his composure disappears.

He pushes his pelvis back against your face, and his voice climbs higher and higher with every flick of your tongue. You drag your thumb up and down his slit.

‘could you, maybe–‘ he breathes, ‘uh-‘

You suck on his clit and he gasps, ‘jesus christ _____, i need your f-fingers inside me, please babe-‘

You can’t help but give him what he wants when he looks at you like that. Cheeks flushed blue, watery eye sockets, trembling shoulders.

You tap against his clit before slipping two fingers inside of him, crooking them, trying to find the right angle. You can hear how wet he is with every pulse of your wrist. You wonder whether it’s worth getting up to grab a vibrator.

You pull back and watch him thrust against your fingers, feel him squeeze his legs around you.

You pick up the pace, more pressure, if you can hit the angle just right, if you can just-

‘h-holy fuck, i- i think i’m going to-‘

‘That’s it…’ you whisper, unsure if he can hear you over the sound of your fingers.

‘holy shit, holy shit, shit-‘ he snaps his head up as he squirts all over your fingers.

‘Fuck yes, Sans. God fucking damn, yes.’ You don’t let up. His body shakes.

‘shit, shit i-!’ He squeals and more fluid shoots against your legs. It drips down your thighs and seeps into the couch cushions. He jerks as smaller spurts follow.

‘Mmm, _yes_ ,’ you growl, and you’re back between his legs. You spread apart his folds and slurp up what you can. He hasn’t come yet, and you don’t want him to until he can’t take it anymore.

‘fucking hell, i- i need to, baby i need to-‘

‘I know. And I promise I’ll make you come. But not yet, not yet, you gotta wait for me.'

‘_____ please...’

‘Shh…’ you slide the flat of your tongue over his clit.

He sobs, ‘please! it feels so fucking good, i just–' He arches his spine, his hands grip your hair as he trails off, 'no i won’t, i- i won’t come until you tell me to,‘ his voice barely a whisper.

He’s losing his mind and you love it.

You want to draw this out for as long as you can, until your wrist hurts, until your whole body hurts from pressing against his odd angles.

You hold him right on the brink of orgasm, eating up how good he’s being, how hard he’s trying not to come for you. You want to make this good for him. You want this orgasm to be fucking incredible. The longer you can edge him, the better it’ll be. He knows it too.

Nothing else exists just for this little moment in time. The world is just this room, hazy and heated. All you taste is the heady air around you, the salt of his sweat on your tongue, and the acidity of his magic, indescribable, intoxicating—

_Bbbrrring. Bbbrrring._

…

_Bbbrrring. Bbbrrring._

Shit.

_Bbbrrring. Bbbrrring._

God you want to ignore it, you so badly want to ignore it. And you would if it were your phone, but you know that ring tone.

The one person Sans never ignores is his brother. And you know from experience that this still applies, even on the brink of a killer orgasm.

You look up at him and slow your hand as he realizes his phone is ringing. You wipe your hand on the side of the couch before reaching down to the pocket of his shorts.

‘shit…’ Sans murmurs, trying to calm down. He instinctively covers himself.

You exhale slowly, ‘Maybe it’s nothing. Let me get it?’ He nods, still shaking.

You clear your throat and wince when your voice cracks. ‘Hello?’

‘Hello Sans!? Somet- Wait, wait you’re not Sans, who-’

‘It’s me, Undyne.’

‘Oh! Oh right, okay, Sans is with you then? Could you, uh, put him on the line?’ You glance over at him.

‘He’s a little busy. I can take a message though. What’s up?’

‘Shit! – Look, I’m sorry, but he has to stop being busy, or whatever. Something uh, something happened to Papyrus, and I really think he should come home.’

‘Wait, what? What happened?’ Sans sits up straight, suddenly very focused.

‘It’s, ah fuck, it’s too hard to explain, just get over here!’

‘Wait, no Undyne, you can’t just -  is he okay?’

‘Just, ugh, things went wrong. He might be okay, but I don’t know for how long. Do skeletons have to breathe – Hey, Alphys, can he breathe? - Look just get here!’

**Click.**

_Beep. Beep. Beep._

…

You stare at the phone in your hand.

And feel cum drying between your legs.

Sans breathes out slowly and you hear a familiar crackling sound. He gets up to put his shorts back on; the only remnants of his genitalia dripping down his femurs.

That’s magic for you.

‘Wait.’ You grab your discarded underwear and clean between his legs. ‘You okay?’ He pulls on his shorts. You snag your sweatpants.

‘fine, m’fine,’ he breathes out, ‘i’m gonna take a shortcut.’ He throws on his jacket.

 You adjust your sweatshirt. ‘I’ll drive and meet you there.’

‘k.’ He blips out of existence.

Only to blip back a second later.

‘shit.’

‘Sans?’

‘magic’s too fuzzy, can’t get there.’

‘Then we’ll both drive, c’mon.’

You scramble to the car, the cold night air helping you sober up. Thank god you don’t pass any cops – you get there in record time.

He’s two steps ahead of you as you cross the landing and reach the front door.

He yanks it open and the two of you step inside.

…

How they managed this you’ll never know.

The first person you see is Papyrus. He’s wearing a pair of slacks and a button-down shirt. Must’ve come home from class not too long ago. And he’s quivering in a chair, completely covered from the shoulders-up in what looks like… you hesitate to say it.

‘It’s supposed to be mochi, in case you were wondering.’ Undyne nervously tells you, shifting from one foot to the other.

‘…how?’ Sans asks, still staring at his brother.

Alphys bounces nervously. ‘Papyrus said he’d help us make enough mochi for the anime convention this Saturday, s-since we’re in charge of the pastries for our group. He said we could use his mixer, but…’

‘But I didn’t wait for him to show me how to use it, okay!? I was an idiot. I know! Chew me out later–'

‘We d-didn’t want to try and get it out ourselves cause, well, just look! It’s stretched through his eye sockets! And it’s all up in his skull, and he hasn’t said anything, and ohmygod, Sans, Sans please say he’ll be alright!’

‘All up in his skull’ is an understatement. It stretches inside and outside of his eye sockets, wraps through his jaw, down his neck, and around his shoulders, almost like webbing. Really thick webbing.

Sans stands motionless, blinks once, twice, and sighs.

‘yeah, yeah he’ll be fine, probably just feels super weird. what’s this stuff made out of?’

‘Glutinous rice flour.’

‘…is it water soluble?’

‘Yes, but we didn’t want to do anything – it’s INSIDE HIS SKULL. INSIDE HIS EYE SOCKETS. We thought he might be seriously injured. I wasn’t about to make it worse! And he’s not talking! He’s ALWAYS talking!’

You turn to Sans. ‘Want me to get some water or something?’

‘yeah. boil some, would you? you know where everything is.’ He says, not taking his eyes off of Papyrus.

‘Sure thing.’ You make your way towards the kitchen, keeping one ear open.

‘Will he still be able to see and shit!?’

‘yeah, he’ll be fine, it just feels really wrong when anything gets shoved into your skull, like watching one of those contortionist videos. It shouldn’t bend like that, shouldn’t go in there.’

‘Dude, Papyrus, if you can hear me, I’m so sorry!’

The chatter goes on as the three of them try to pry what they can off of Papyrus’s face.

You appear with the boiling water and watch as Sans cleans out the inside of his brother’s skull. Sans finally manages to free his jaw.

‘S-SO…’

‘Papyrus! Papyrus are you okay!? I’m so sorry dude!’

‘SO SO WEIRD! OH MY GOD SANS THAT FEELS WEIRD!’

‘sorry, but it’s gotta come out, and you can’t exactly see to do it yourself.’

‘OH MY GOD THIS FEELS SO WRONG – THE CONTORTIONIST THING YOU MENTIONED? EXACTLY LIKE THAT. BUT WORSE.’

‘heh. one time when you were a kid i tried to get you to eat peas. turned my back for a second, and there you were plunging em’ into your eye sockets. that was a time.’

‘AH YES PEAS, THE ONLY VEGETABLE I HAVE YET TO BEST!’

‘heh, you were a cute kid,’ Sans chuckles.

‘THE CUTEST!’

‘alright, almost done.’ Sans pulls the towel out of Papyrus’s head.

‘I SEE THE LIGHT!’ Papyrus glances around. ‘AND THE WORLD’S BIGGEST MESS. THIS RIVALS YOUR OLD BEDROOM SANS.’

‘You sure you’re alright Papyrus?’

‘A LITTLE GROSSED OUT, BUT OTHERWISE PERFECTLY FINE.’

‘Oh thank God.’ Undyne sinks into a chair, and Alphys pats her back reassuringly.

‘I’M REALLY ALRIGHT UNDYNE. NOT DEAD – SEE?’ He strikes a cool guy pose, the kind that only cool guys make. ‘IN FACT, YOU MAY HAVE OVERREACTED A LITTLE.’

‘I did not! I don’t know how your weird skeleton body works! I thought I had actually broken you.’

‘B-better to be safe than sorry Papyrus.’

‘THAT’S TRUE! I’M GLAD THAT I HAVE SUCH KIND FRIENDS!’

‘Oh stop being such a nerd. Sides’ I still messed up your kitchen pretty bad…’

‘HEY, IF IT ISN’T ON FIRE, I’D SAY THE DAY TURNED OUT RATHER WELL.’

Undyne snickers.

Alphys cocks her head. ‘S-sans, are you alright? You don’t look so good.’

‘…hmm? oh. nah. m’fine, don’t worry about me.’

‘O-okay… It’s just I’ve never seen that color on you before.’

‘color…?’

You look around the room. ‘Man, this’ll take you guys awhile to clean up, huh.’

‘YES. THE SOONER WE GET STARTED THE BETTER.’

‘I call mop duty!’ Undyne races to the broom closet.

‘AW, BUT MOPPING IS MY FAVORITE!’

‘Everything’s your favorite!’

‘SANS, _____, WHY DON’T YOU STAY THE NIGHT? IT’S LATE AND IT’S NOT GOOD TO DRIVE WHEN YOU’RE COMING DOWN FROM AN ADRENALINE HIGH, OR SO I HEAR.’

You differ to Sans. ‘we came all the way over here, might as well stay.’ Papyrus visibly relaxes.

‘Sounds good to me. We’ll be up in Sans’ room if you need anything Papyrus. That cool?’

‘VERY COOL MY COOL FRIEND.’

‘Later punks!’

Alphys waves and you swear she winks at you. You try not to think too hard about it.

~~-~~

Sans closes and locks the door behind him before sitting on the edge of his bed, head in his hands. He stares straight into space.

You sit down next to him and trace your fingers over his spine, feeling tiny sparks of magic jump across your arms. ‘Well that happened.’

‘it did.’ He breathes out slowly.

‘You okay?’

‘yeah, i’m fine.’

You fall back onto his bed and stare at the ceiling. ‘The way she said it I thought he was dying or something, had a fucking heart attack.’

He looks askance at you, the harsh florescent light emphasizing the dark circles beneath his eye sockets.

You close your eyes and chuckle, ‘He wasn’t obviously, but that’s where I went.’

‘yeah, heh. me too.’

You open one eye and gaze at him. ‘But he didn’t. Didn’t even phase him. The beanpole is right downstairs, reaching high shelves and unintentionally posing for vogue.’

That one gets a smile out of him. ‘yeah… yeah, nothing keeps him down for long. isn’t he great?’

‘The greatest,’ you yawn.

The bed shifts as he flops down next to you. You grab his hand and feel sparks of magic tingle through your body, like little jolts of electricity.

‘Sans… Do you remember where we left off?’

‘don’t remind me. m’ struggling as it is.’

‘You worried about them hearing us?’

‘yeah.’

‘They’re not exactly paying attention to us. And they’re downstairs. Papyrus is occupied. We could give it a shot, you won’t hear any complaints from me. Besides, I still want you to come for me, baby boy.’ You feel him shiver.

‘oh fuck, don’t call me that.’

You think for a second. ‘I have an idea.’

‘oh no.’

‘Oh YES!’ You do your best MTT impression. He snickers. ‘If we wanna be quiet, we can’t continue where we left off.’

‘yup,’ he chuckles, his cheekbones darkening.

‘So why don’t we try something a little different? It’s up to you, but I think we can make it work.’

You can see him deliberate for a minute. ‘…will you make sure the door’s locked?’

You know he locked it, but you get up to check anyway.

You put your hands on his hipbones, pull him towards you, and bite down on his neck.

He gasps, ‘it-it won’t take much-’

‘Mmm, I know, but let me enjoy you.’ You whisper.

He flushes blue all the way down to his shoulders. You’re pretty sure he’s thinking about how his brother is just downstairs. Well, you’ll just have to get him to stop thinking about it.

You push him back towards the bed, and slip off his jacket as you go. You drop your sweatpants, and snap the waistband of his shorts.

You sit criss-cross and ask him to sit in your lap. He slips his legs over your thighs, hands around your back, under your shirt.

You run your fingers up and down his spine, scratching between the little indents and divots. ‘Let me have your cock this time.’

Static fills your ears for a moment before fading into the soft crackling sounds of a campfire. He groans and his grip tightens.

You can feel the heat radiating off his cock. He’s rock hard, precum already beading at the tip.

‘i’m still… from earlier.’

‘Mmm, I know. Let me take care of that.’

He buries his face in your neck as you run your hands over his rib cage and down his spine. He bites down on your shoulder when you finger his tailbone.

‘You okay?’

‘y-yeah, sorry, i just—‘

‘Don’t be.’

You lightly run your fingers up and down his shaft before wrapping your hand around him.

His hipbones jut into your body, as he muffles himself in your shoulder, your hair a sound barrier.

You reach between your legs and slide your fingers up and down your slit, gathering the fluid that’s collected there. You remove your hand and it glistens in the light as thick, translucent mucus stretches between your fingers.

‘f-fuck.’ You hadn’t noticed him watching.

You make a show of wrapping that hand around his cock, mixing it with his precum. It’s plenty of lubrication, and you get a nice, steady rhythm going.

You whisper to him, ‘You’ve been waiting for this for a long time, haven’t you, baby? All evening… I promised, didn’t I? And I keep my promises. But this time you’ll come for me against my cunt, without a sound.’ You shiver at the delicious feeling of his phalanges digging into your back. He drags them across your skin, leaving giant red welts.

His teeth sink deeper into your neck. He lets out a tiny whimper that you can barely catch, but it’s enough to get your blood boiling.

You whisper just above his temple. ‘You know what I want to do, Sans? I want to slam you back into this bed, take your tailbone between my teeth, suck on it, make you squeal for me.’

‘f-fuck,’ he gasps, ‘_____ i can't-’

‘But sometimes…’ you continue under your breath, ‘Sometimes this is what I want. Sometimes I just wanna feel you in my arms, feel your hipbones against mine, and watch you come because of me. You’re everything I want.’

The sharp ridges of his nasal cavity press into your skin. His grip on your back tightens, bordering on painful.

‘That’s it…’ You kiss his temple. A bead of precum slides down his shaft.

You squeeze. His chest cavity heaves. You can feel his body tense; his arms tighten around you.  

‘You gonna come for me?’ He nods into your neck. You reach around with your unoccupied hand and tease the tip of his tailbone. He grinds his pelvis against your thighs. ‘Come for me Sans. Come whenever you’re ready baby boy.’

You hear his jaw crack, feel his toes clench. Three more quick thrusts, and he growls into your shoulder, the sound muffled by your hair, as hot, thick, spurts of cum shoot between the two of you. It lands on your stomach, on your cunt, and drips down his cock. You take in a shuddering breath as you watch him come undone, and milk him for all he's worth. He rubs his forehead into your shoulder, his chest cavity still heaving.

You move to kiss his temple, his neck, his shoulder, and absentmindedly brush your thumb over your swollen clit.

He rubs small circles over the scratches on your back before running his hands down your sides, under your shirt, over your breasts. 

‘You know what I want now, Sans?’ You whisper.

‘can i-‘

You tilt your head, and hear the footsteps of someone running up the stairs.

You both freeze.

They stop before Sans’s door, and knock on it in a way that shakes the whole room.

‘SANS? WE UH, WELL, WE KIND OF HAVE A PROBLEM.’

Sans clears his throat.

‘problem?’ He calls through the door.

‘YEAH UH, WELL, UNDYNE KIND OF BROKE MY MIXER. AND BY BROKE IT, I MEAN THERE ARE EXPOSED WIRES AND SPARKS FLYING. YOU TELL ME NOT TO TOUCH ANY ELECTRICAL STUFF UNLESS I HAVE TO, AND ALPHYS SAYS SHE DOESN’T WANT TO MAKE IT WORSE, EVEN THOUGH SHE PROBABLY WOULDN'T. COULD YOU COME TAKE A LOOK AT IT?’

You’re already nodding before Sans looks at you. ‘sure thing papyrus, just give me uh, a couple minutes. don’t touch anything.’

‘OKAY! AND I WON’T!’ His footsteps echo back down the hall.

You laugh as he wraps his arms around you and mutters about electrical appliances into your neck.

‘i’m sorry.’

‘Why?’

‘you haven’t come yet, and i don’t know how long this is gonna take.’

‘Sans, babe, if you can wait through a mixer crisis, I can wait through a mixer crisis.’

He sighs, ‘still.’

‘It’s not a big deal – we’ll both get to experience sexual frustration, and subsequent alleviation.’ You kiss the back of his hand.

‘we make quite the prickly pear.’

‘…Is that a type of cactus?’

‘yes.’

**Author's Note:**

> This plot? Not sure what it is or where it came from. But, I had fun with it and that's all that matters, right?


End file.
